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763
FXUS62 KGSP 160959
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
559 AM EDT Thu May 16 2024

.SYNOPSIS...
Brief high pressure brings a dry day today. Showers and scattered
thunderstorms return Friday and continue into the weekend. Isolated
afternoon and evening showers and thunderstorms are expected early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
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Early morning update...No major changes to the forecast this
morning.  Fog has expanded, as anticipated, all up and down the
I-77 corridor and into most of the NC Piedmont and Foothills zones.
The Dense Fog Advisory will be allowed to continue.  Otherwise,
little change apart from touching up the dewpoint, wind, and
temperature trends based on the latest observations.


As of 301 AM EDT Thursday: It`s a quiet night across the western
Carolinas for the most part, with building heights aloft and high
pressure filtering in at the surface.  Dewpoints are considerably
lower than they were this time last night, signifying the
drying trend we`re on now that active weather has pivoted east.
Nonetheless, there`s a broad area of the NC Piedmont where they`re
high enough to produce fog in light of clear skies and light winds.
Lots of stations are now reporting 1/4-1/2SM visibility, so that`ll
precipitate a Dense Fog Advisory issued with the 330AM forecast
package, which will run until 14Z / 10AM LT, when fog will almost
certaintly have scattered out.  Temps this morning should drop
into the mid/upper 50s.

Today will be quiet with dry W winds for most of the day.  Good
solar insolation combined with a slight downslope component to
winds across parts of the Piedmont and Upstate will allow highs to
surge into the mid 80s across most of the region.  Other than some
scattered fair-weather cumulus, skies will remain clear through
the day.  The exception will be the NC mountains, where lingering
moisture may support some brief upslope sprinkles, mainly on west-
facing slopes.  Tonight, high clouds will begin building again
from the west. Lows will drop to around 60 outside the mountains.
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&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 255 AM EDT Thursday: An active weather pattern returns for
Friday and Saturday as a stacked low pressure system slowly moves
across the area. Precip chances ramp up Friday and Friday night,
then maxes out on Saturday as deep moisture and strong forcing move
in with the low pressure. PW values will be quite high, and with
periods of showers and thunderstorms, areas of heavy rain will be
possible, which could lead to isolated flooding. The amount of QPF
is still uncertain as convection along the Gulf Coast could
interrupt better moisture inflow keeping the heavier rain to our
south. Severe thunderstorm chances are also uncertain with weak
lapse rates keeping instability on the low side, even with the upper
low moving in. Lack of strong heating could also limit instability.
That said, there could be an uptick in instability on Saturday,
along with some DCAPE. Strong shear develops with strong turning in
the low levels on Saturday. Therefore, this will need to be watched
as the event approaches. Precip chances taper off Saturday night.
Highs will be near to slightly above normal Friday then drop a
couple of degrees for Saturday. Lows Friday night nearly 10 degrees
above normal drop to around 5 degrees above normal Saturday night.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 315 AM EDT Thursday: The ECMWF has now joined the GFS and
Canadian in slowing the eastward movement of the stacked low
pressure system. This allows showers and thunderstorms to redevelop
across the area Sunday then quickly tapering off Sunday night. Drier
high pressure builds on on Monday, but enough moisture lingers for
scattered diurnal convection across the mountains with isolated
convection elsewhere. Only isolate diurnal convection expected
across the mountains Tuesday. Chance of diurnal convection increases
Wednesday as a cold front approaches from the west. Temps on Sunday
are uncertain as some guidance shows a CAD like feature developing.
Do show cooler temps across portions of the area to show the trend,
but held off on full CAD temps due to uncertainty. A warming trend
then takes place through the period with highs around 5 degrees
above normal by Wednesday.

&&

.AVIATION /10Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Generally quiet across the area, with the
main concern for the entire TAF period being visibility through
daybreak Thursday.  Already, there`s a corridor of dense fog
developing across the NC Piedmont, with KHKY already seeing LIFR
restrictions leading up to the 06z TAF issuance!  Expect gradual
expansion of this area and worsening of overall conditions through
daybreak - LIFR to VLIFR restrictions seem likely at this point -
after which fog will quickly scatter out.  Thereafter, we can
expect pleasant VFR conditions through Thursday and Thursday
night, with some scattered capped cu likely to develop during the
afternoon.  Winds will be mostly out of the NW, although some of
the southernmost zones could see a period of light WSW winds during
the afternoon hours, quickly toggling back to NW in the evening.
Mountain valley fog/low stratus may occur again Thursday night.

Outlook: Convection active weather and associated flight
restrictions will return Friday, likely continuing through the
weekend. Late night/early morning restrictions in low stratus
and/or fog will also be possible. Drier weather is expected to
return early in the next work week.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Dense Fog Advisory until 10 AM EDT this morning for NCZ035-036-
     056-057-068>072-082-502-504-506-508.
SC...Dense Fog Advisory until 10 AM EDT this morning for SCZ008-009-
     013-014.

&&

$$

SYNOPSIS...RWH
NEAR TERM...MPR
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...MPR